Frailty is widely viewed by geriatricians as increasingly prevalent with old age. Elderly individuals who are frail are identified as a high risk subset of older adults who are at most risk for hospitalization, functional decline and early morbidity and mortality. The mechanisms by which frailty develop are unclear and may be related to underlying disease processes. However, it is likely that there are age-related variations in physiologic parameters that are exaggerated in some individuals and which may influence the development of this syndrome. The specific aims are: 1) to characterize the association of a standardized defined phenotype of frailty with skeletal muscle mass and function as assessed by muscle power and strength; 2) to characterize the association between frailty and cortisol secretion, sex steroid levels, thyroid function, immune system function, and levels of cytokines; and 3) to determine the relationship between physiologic and molecular parameters in the frail. To help identify underlying physiologic factors that may allow earlier interventions and head off the development of the syndrome of frailty, we will identify frail and non-frail individuals from a variety of sources throughout Johns Hopkins and surrounding centers. Age >70 individuals will be screened excluding those with medical conditions that may cause abnormalities in the definition of frailty, such as Parkinson's disease, cerebral vascular accident with residual hemiparesis, symptomatic rheumatoid disease, symptomatic cardiovascular disease, and level of abnormality in the Folstein MiniMental score. We will review medical charts for these and then perform the following exam on those who are not excluded secondary to medical diagnosis. Frailty is defined as having 3-5 components of a syndrome consisting of grip strength weakness, slow-timed walking speed over 15 feet, subjective assessment of fatigue and low physical activity, as well as unintentional weight loss of 5% or greater in the past 2 years. Using the same exam, we will identify a group of age-matched controls that meet none of the above criteria. The frail and non-frail participants will be enrolled in the second portion of the study at the GCRC. Anthropometric measurements will be performed after a nurse's exam involving skin fold, biceps, tricep and inner thigh measurements using calipher and tape measurements. We will perform strength and power measurements using the Biodex isokinetic exercise machine in order to characterize the power and function of the gastrocnemius, quadraceps, hip extensors and biceps (performed in the Physical Therapy Department). A DEXA scan will be performed only on the GCRC Lunar Prodigy in order to take measurements of total lean body mass, total fat mass, and bone mineral density. Blood samples will be drawn by GCRC staff, as well as a urine collection (24-hr sample)returned to the GCRC the next day for analysis.